Nowadays, continuous manufacturing processes, such as a roll-to-roll manufacturing process, has been vastly applied in various industries including flat panel display industry, flexible electronic industry and solar cell industry, etc., owing to their advantageous characteristics of being able to produce a mass of products in a comparatively short period of time.
However, in those rapid mass production processes, it is possible to have a plenty of defective products being produced if a decision can not be made immediately for shutting down the production processes in the case of an abnormality. Thus, it is common for those rapid mass production processes to have certain monitoring devices or measuring devices installed therein so as to be used for detecting any abnormality in time, and therefore, adjusting the manufacturing parameters of the corresponding mass production process accordingly, or even shutting down the whole process for major revisions.
There are already many monitoring/measuring apparatuses available for monitoring surface structure, film thickness or surface roughness of a product so as to prevent the surface of the product from being scratched. It is common to design those conventional monitoring/measuring apparatuses as non-contact measuring modules, whereas some of those non-contact measuring modules can be optical measuring apparatuses, such as those disclosed in U.S. Pat. Nos. 7,605,929, 7,411,685, 6,806,459, 6,775,011. It is noted that the optical measuring apparatuses disclosed in U.S. Pat. Nos. 7,605,929 and 7,411,685 are designed to be movable while allowing the corresponding device-under-test (DUT) to be stationary during being measured, but on the contrary that the optical measuring apparatuses disclosed in U.S. Pat. Nos. 6,806,459 and 6,775,011 are stationary while enabling the DUT to move during the measuring.
For measuring DUTs with high surface reflectivity, the sampling frequency of the measuring apparatus can be increased for increasing the lateral resolution. On the other hand, for DUTs with low surface reflectivity, it may unable to obtain the required lateral resolution simply by increasing the sampling frequency of the measuring apparatus, since the increasing of sampling frequency may cause the exposure of each and every location of signal acquisition to be not sufficient, resulting that the measuring apparatus may unable to acquire complete location signals.
It is noted that, for any optical measurement, sufficient exposure time is the key element for acquiring surface signals of a product to be measured. Accordingly, while performing an optical measurement in a rapid continuous manufacturing process where the products to be measured are being transported at high speed, it is likely that the optical measurement will not be able to acquire sufficient luminous intensity signal at the same position in time when the products are objects with low reflectivity, such as optical films. Thus, the stationary optical measuring apparatuses may incapable of being used to acquire sufficient luminous intensity signal at the same position in time for products that are being transported at high speed.
On the other hand, although some optical measuring apparatuses are designed to be movable, they are restricted for measuring products that are stationary and thus may not be used for measuring products that are being transported at high speed.